In the rapid digestion of their food they are assisted by a special organ which grinds down such items as grain, gravel, nails, or needles, swallowed in mistake or from caprice or curiosity, with astonishing facility. They prefer feeding nearly all day, and when fully crammed they sometimes become as plump as ortolans, or as well-fed quails, whose skin bursts when they fall to the gun. But when the appetite is urgent, obesity does not by any means preclude hunger. Twelve hours’ fast and snow and a change of wind are very urgent facts in the lives of these quick creatures in the autumn of the year, and then begins that sudden migration which the lighthouse-keepers have observed. It is impossible to imagine creatures more practical and full of action and freer from “presentiments” than birds, engaged as they are from day to day snatching their food at Nature’s board. Perhaps we may compare them to the guests of Macbeth, since all goes well so long as the ghost abstains from making his appearance; but very suddenly sometimes, in the case of the northern birds, the spectre of hunger puts them to flight. Fat or lean, they must go on the instant, and that is why they arrive pell-mell upon our coast; but, as the country to be cleared of its birds of summer is extensive, and the distances of the journeys various, they naturally arrive at intervals. The migrations of birds are world-wide. The birds of North America make corresponding movements to those of Northern Europe, travelling in a north-easterly and south-westerly direction and at the same seasons. The countries of the Gulf of Mexico form the chief retreat of the North American migrants, especially Mexico itself, with its three zones and great variety of climate. But some of them go as far as the West Indies and New Granada. A great number winter in the Southern States. Their method of migration is the same as that which has been described elsewhere. They follow the routes marked out by nature. The kinds of birds are in many cases the same, or they are at least American representatives of the same families that form the migrants of the Old World. They travel southwards in the autumn and return again in spring. The migrants of the southern hemisphere are constrained by their situation to reverse the direction of their periodic movements, flying northwards to escape the rigor of winter and returning south in spring. From March to September some of the most inhospitable regions of the south are quite deserted; even the wingless penguins quit their native shores of Tierra del Fuego and the Falkland Islands after the breeding season and swim to milder regions, while many of the birds which have bred in Patagonia and Southern Chili depart on the approach of winter. The same rules, according to Gould, govern the movements of birds in Australia, where several species migrate in summer to the southern portion of the Continent and to Tasmania to breed.—_Edinburgh Review._